When a base station tries to allocate a downlink persistent resource, it transmits a DL persistent allocation A-MAP IE to a terminal to which the downlink resource should be allocated. Upon reception of the DL persistent allocation A-MAP IE, the terminal periodically receives the allocated downlink resource based on information included in the corresponding IE, and receives packets transmitted by the base station using the allocated resource. Also, when the base station tries to allocate an uplink persistent resource, it transmits an UL persistent allocation A-MAP IE to a terminal to which the uplink resource should be allocated. Upon reception of the UL persistent allocation A-MAP IE, the uplink resource is periodically allocated to the terminal based on information included in the corresponding IE and the terminal transmits a packet to the base station using the allocated resource.
FIG. 1 illustrates a general persistent resource allocation method through a persistent resource allocation message (for example, Persistent Allocation A-MAP IE). Especially, FIG. 1A illustrates a downlink (DL) persistent resource allocation, and FIG. 1B illustrates an uplink (UL) persistent resource allocation.
Hereinafter, a DL persistent resource allocation will be exemplarily described.
First, a terminal receives a DL Persistent Allocation A-MAP IE from a base station. The terminal receives an allocated persistent resource using the received DL Persistent Allocation A-MAP IE, and receives data packets from the base station using the allocated persistent resource. Also, the terminal receives data packets at the same position as a position, to which a persistent resource has been initially allocated, at each predetermined period, namely, at each predetermined frame interval based on persistent allocation period information included in the DL Persistent Allocation A-MAP IE.
As illustrated in FIG. 1A, under a bad channel condition between the base station and the terminal, the terminal does not immediately receive the DL Persistent Allocation A-MAP IE transmitted from the base station, but receive the A-MAP IE after performing a retransmission process. This causes a persistent pattern of an unnecessary packet transmission delay not only for a first packet indicated by the DL Persistent Allocation A-MAP IE but also for every new packet generated after the first packet.
However, the packets allocated through the DL Persistent Allocation A-MAP IE generally correspond to a real-time service, such as VoIP. Hence, the packets of the service are sensitive to the delay. Therefore, unless more than preset delay requirements are met, the delayed packets are deleted at an upper layer, so transmission thereof is failed.
Especially, when a persistently allocated resource is allocated to a terminal by two or more retransmissions of the DL Persistent Allocation A-MAP IE and a channel condition is bad at a specific time point, a corresponding packet is further delayed.